Activation and inhibition of rat hepatic UDP-glucuronyltransferase by mercuric acetate.
1. The effects of mercuric acetate on glucuronide conjugation of bilirubin and 4-methylumbelliferone in vitro represent a new type of modifier of UDP-glucuronyltransferase activity. 2. Bilirubin UDPG-transferase was normally activated (optimally 4-fold), inhibition was seen only at high concn. of Hg2+. 4-Methylumbelliferone UDPG-transferase was normally inhibited by Hg2+, but at high concn. of UDPGA (10 mmol/l) slight activation was seen. 3. Activation of bilirubin conjugation was unaffected by Mg2+ concn., indicating that the mechanism of Hg2+ activation differs from that caused by Mg2+. 4. Glucuronidation of bilirubin in liver microsomes from control rats, or rats treated with phenobarbital, methylcholanthrene or TCDD respond similarly to Hg2+, confirming with phenobarbital, methylcholanthrene or TCDD respond similarly to Hg2+, confirming the view that bilirubin conjugation is not inducible by these inducers.
D000818:Animals; D001663:Bilirubin / Q000378:metabolism; D004072:Digitonin / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D005965:Glucuronates / Q000378:metabolism; D014453:Glucuronosyltransferase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006923:Hymecromone / Q000378:metabolism; D008297:Male; D008628:Mercury / Q000494:pharmacology*; D008862:Microsomes, Liver / Q000201:enzymology*; D051381:Rats
D005965:Glucuronates; D006923:Hymecromone; D014453:Glucuronosyltransferase; D008628:Mercury; D004072:Digitonin; C029823:mercuric acetate; D001663:Bilirubin